The overriding theme Tuesday during Marcell Dareus' first interaction with reporters this year was that he is trying to put the past behind him and concentrate his energy on becoming a better player for the Buffalo Bills.

Dareus has been shielded from the media ever since his two arrests in May, one for possession of synthetic marijuana and drug paraphernalia in Alabama and the other for illegal street racing in the Buffalo suburb of Hamburg.

"I'm just trying to stay focused," Dareus said during a six-minute exchange. "A lot of issues come from other people and they distract you from what your main focus and goal is, so I've been keeping my eyes on the prize and doing the best I can. Mentally I'm in a good state and I'm just happy to be back out here."

Dareus reported to camp not ready to hit the field immediately, and he said passing his conditioning test was more of a mental issue rather than a physical one. Once he got past that obstacle, he said it's been full speed ahead, and to his credit, he has looked good in practice and in the preseason games.

"Camp's been great this year," he said. "(Coach Doug) Marrone has put in a lot of thought into what we're doing and what we're preparing for. I'm excited what we have in and what we're looking forward to."

The 24-year-old Dareus said he has received constant support and words of encouragement from Marrone and his teammates in his quest to put his troubles behind him.

"The team is so supportive, the coach has been outstanding, and it's a great atmosphere to be around," he said. "We all have each others' backs. They've been coming to me with great advice. I don't have any worries, just going to put my best foot forward and we're all riding together and doing the best we can for the Buffalo Bills."

Dareus would not answer questions about his legal situation, and he said he has not heard from the NFL in relation to a possible suspension that he could face.

Watkins sits out again: Wide receiver Sammy Watkins' rib injury apparently is not serious, though there has still been no official word on what exactly the injury is, and how much time Watkins might miss.

The rookie took part in individual drills during practice Tuesday, but watched the 11-on-11 portions.

"It's all about resting me right now, and I'm doing all right," he said. "I'm fine, I could go out there and practice if I need to. The thing is doing it without pain, but I could play a full game right now. It's just being safe."

Watkins wasn't sure how he got hurt, saying it was "just an awkward hit. I was just in the play, it just happened. Injuries happen during the game, but anybody can play hurt or nicked up. That's part of sports."

Watkins does not know if he'll be able to play in the Bills preseason home opener at Ralph Wilson Stadium on Saturday, but he said if it was a regular-season game, there would be no doubt that he'd be out there.

Bills do the ALS challenge: At the end of practice, the Bills moved down to one end of the field and participated in the ALS Ice Bucket Challenge en masse. Russ Brandon did the talking, and he nominated ESPN personality Chris Berman to do the challenge. Brandon must have been unaware that Berman already did the deed last week with other ESPN personalities.

Brandon, coach Doug Marrone, and general manager Doug Whaley and as many players as there were buckets for were doused as the remaining crowd in the stands cheered.

Practice squad: The NFL and the NFL Players Association have agreed to expand practice squads from eight to 10 players for the 2014 and 2015 seasons. Also, eligibility rules have been altered.

First, a player must have a minimum of six games — up from the current three games — on a practice squad in order for that season to count as one of the player's three permissible seasons of service. Second, each club will be permitted to sign a maximum of two practice squad players who have earned no more than two accrued seasons of free agency credit. Absent this exception, a player who has earned one or more accrued seasons would not be eligible for a practice squad unless the player spent fewer than nine games on a club's 46-player active list in each of his accrued seasons.

"Development is the key," said Marrone, who loves the idea. "It's a league that doesn't really have a farm system for players. If you looked at us last year, we really didn't go outside when we had injuries, we were able to upgrade from the practice squad, and that's not going to change. So I would be for that."